This invention relates generally to slide fasteners and in particular to an automatically locking slider for slide fasteners. Still more particularly, the invention concerns an automatic slider lock mechanism of the type including a leaf spring with a locking pawl at one end thereof which normally projects into the guide channel in the slider body to lock the slider against movement on a pair of fastener stringers and which retracts therefrom to unlock the slider when a pull is exerted on the pull tab of the slider.
In the automatic slider lock mechanism of the above defined type, the locking leaf spring has heretofore been supported substantially at its mid-point by suitable means mounted more or less centrally on the top wing of the slider body with respect to its longitudinal dimension. According to this prior art arrangement, the locking leaf spring is relatively easy to be displaced or deformed when twisted by the application of crosswise pulling forces to the pull tab. The mechanism will then be unable to lock the slider properly on a pair of fastener stringers.
The prior art slider lock mechanism is also objectionable in that the curved portion of its locking leaf spring, which portion is the principal part lending the desired resiliency to the spring, is located too close to the point on the locking leaf spring where the pull tab of the slider is pivotally connected thereto. The curved spring portion thus arranged with respect to the slider pull tab is directly subjected to high stresses resulting from the exertion of endwise or crosswise pulling forces on the pull tab. This can significantly shorten the service life of the locking leaf spring and of the slider itself.